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Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/ref/set_transaction.sgml | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/doc/src/sgml/ref/set_transaction.sgml b/doc/src/sgml/ref/set_transaction.sgml index 2c57f45511b..f864bbf6a61 100644 --- a/doc/src/sgml/ref/set_transaction.sgml +++ b/doc/src/sgml/ref/set_transaction.sgml @@ -135,6 +135,17 @@ SET SESSION CHARACTERISTICS AS TRANSACTION <replaceable class="parameter">transa among those listed. This is a high-level notion of read-only that does not prevent all writes to disk. </para> + + <para> + The <literal>DEFERRABLE</literal> transaction property has no effect + unless the transaction is also <literal>SERIALIZABLE</literal> and + <literal>READ ONLY</literal>. When all of these properties are set on a + transaction, the transaction may block when first acquiring its snapshot, + after which it is able to run without the normal overhead of a + <literal>SERIALIZABLE</literal> transaction and without any risk of + contributing to or being cancelled by a serialization failure. This mode + is well suited for long-running reports or backups. + </para> </refsect1> <refsect1> |